Caption: Intelligent label chip. Computer artwork of a radio frequency identification (RFID) chip held between a woman's finger and thumb. RFID chips consist of a plastic circuit printed onto foil and antennae for receiving and transmitting radio waves. Plastic circuits are cheaper than silicon, although at the moment they are also slower and store less data. RFID chips are already used in animal tagging, anti-theft systems, building access control, shipment tracking and in 'electronic cash' cards used on transport systems. They could replace barcodes, storing not only an item's price but also its expiry date, weight and other information.